Advances in CMOS and biCMOS technologies has enabled RFIC suppliers like Infineon Technologies and Silicon Laboratories to develop single-chip multiband radio transceivers for emerging cellular and mobile phones. In fact, there are many others with monolithic multiband solutions for the cellular market. But, with increasing data traffic, network operators are adding high-speed data technologies such as Enhanced-GPRS (EDGE) and wideband-CDMA (WCDMA) onto their existing GSM networks, thus creating the demand for multimode cellular handsets that can support GSM, GPRS, EDGE and WCDMA standards. As the drive for a multimode solution gathers momentum, handset makers are looking for more integrated transceivers — multiband, multimode on a single semiconductor die.

No doubt, multichip modules are serving the need. However, such RF solutions for multimode handsets cost more, occupy extra space and consume higher power. Nevertheless, they require longer design cycle time, which means delayed introduction of the product to the market. To address these issues in multimode RF transceivers, and enable handset makers to realize the full benefit of the emerging cellular and mobile phone standards, RF semiconductor suppliers like Sequoia Communications and Tropian Inc. have emerged to create a true multimode transceiver chip using a common basic architecture across all modes.

Sequoia has merged its polar architecture with 0.18 micron silicon germanium (SiGe) biCMOS process technology to develop a single-chip multimode transceiver. According to Sequoia, polar modulation, the standard architecture in GSM, which is also being adopted in EDGE, has never been successfully implemented for WCDMA until now. Sequoia Communications' FullSpectra polar architecture solves this RF design dilemma and delivers the highest impact in WCDMA, where power consumption and complexity are problematic (for details, see “Unprecedented single-chip, multimode WEDGE RF transceiver for 3G handsets,” p. 74).

Because cost and long battery life are essential for broadband adoption of multimode handsets, the company has addressed those issues in its latest release for multimode WEDGE application. According to Scott Smyser, a director and principal analyst for wireless networking research at iSuppli, “Cost and power consumption are critical issues in 3G handsets. Based on our recent research into RF transceiver architectures, it's clear to us that polar modulation is the key to achieving competitive cost and power in the RF section of the 3G phones. Getting polar to work in all modes, especially WCDMA, has been the major hurdle to date.”

Another start-up to combine advances in CMOS with polar modulation is Tropian, who is coming out of stealth mode this month. Implementing its patented polar modulation technology, called Polar Impact, with direct conversion receiver architecture, Tropian has readied its first multimode quad-band RF transceiver for GSM/GPRS/EDGE standards. According to Brian Modoff, senior wireless equipment analyst at Deutsche Bank, GSM, GPRS and EDGE will represent the largest portion of the wireless handset market in 2005 and early 2006, with 3G WCDMA and EDGE volumes beginning to dominate in 2006. “The market is clearly evolving to accommodate demand for high-functionality, feature-rich handsets,” Modoff commented. “Smaller and more efficient transceivers will be critical to the success of EDGE and manufacturers are looking to capitalize on it.”

Tropian's Timestar transceiver with Polar Impact technology is expected to go into full production in the first quarter next year. The developer said that its Polar Impact technology is a unique RF architecture that can be largely implemented in digital logic. Hence, it is amenable to high levels of integration on standard, high-volume, foundry CMOS processes. Digital implementations are inherently more immune to performance changes due to temperature, supply, process variations and aging.

As these new single-chip multimode transceivers herald a new era in RF IC integration, resulting in reduced size, as well as lower cost and power consumption, they are poised to propel multiband, multimode 3G handsets into widespread use. Today's economy needs such drivers.

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